The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on March. The horizontal axis is the day, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Clouds

The month of March in West Valley experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 59% throughout the month.

The clearest day of the month is March 31, with clear, mostly clear, or partly cloudy conditions 42% of the time.

For reference, on January 16, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 65%, while on August 3, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 82%.

Precipitation

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In West Valley, the chance of a wet day over the course of March is rapidly decreasing, starting the month at 28% and ending it at 21%.

For reference, the year's highest daily chance of a wet day is 37% on December 1, and its lowest chance is 4% on August 5.

Over the course of March in West Valley, the chance of a day with only rain decreases from 23% to 20%, the chance of a day with mixed snow and rain decreases from 3% to 1%, and the chance of a day with only snow remains an essentially constant 1% throughout.

The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day rainfall during March in West Valley is gradually decreasing, starting the month at 1.5 inches, when it rarely exceeds 2.9 inches or falls below 0.4 inches, and ending the month at 1.1 inches, when it rarely exceeds 2.1 inches or falls below 0.3 inches.

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average liquid-equivalent snowfall.

Snowfall

We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. As with rainfall, we consider the liquid-equivalent snowfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day liquid-equivalent snowfall during March in West Valley is essentially constant, remaining about 0.1 inches throughout, and rarely exceeding 0.6 inches or falling below -0.0 inches.

The average liquid-equivalent snowfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average rainfall.

Sun

Over the course of March in West Valley, the length of the day is rapidly increasing. From the start to the end of the month, the length of the day increases by 1 hour, 40 minutes, implying an average daily increase of 3 minutes, 20 seconds, and weekly increase of 23 minutes, 19 seconds.

The shortest day of the month is March 1, with 11 hours, 7 minutes of daylight and the longest day is March 31, with 12 hours, 47 minutes of daylight.

The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise of the month in West Valley is 6:24 AM on March 10 and the latest sunrise is 58 minutes later at 7:22 AM on March 11.

The earliest sunset is 5:48 PM on March 1 and the latest sunset is 1 hour, 42 minutes later at 7:30 PM on March 31.

Daylight saving time (DST) starts at 3:00 AM on March 11, 2018, shifting sunrise and sunset to be an hour later.

For reference, on June 21, the longest day of the year, the Sun rises at 5:09 AM and sets 15 hours, 50 minutes later, at 8:59 PM, while on December 21, the shortest day of the year, it rises at 7:43 AM and sets 8 hours, 34 minutes later, at 4:17 PM.

The solar day over the course of March. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray. The transitions to and from daylight saving time are indicated by the 'DST' labels.

Humidity

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

The chance that a given day will be muggy in West Valley is essentially constant during March, remaining around 0% throughout.

For reference, on July 16, the muggiest day of the year, there are muggy conditions 0% of the time, while on January 1, the least muggy day of the year, there are muggy conditions 0% of the time.

Wind

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in West Valley is gradually increasing during March, increasing from 6.5 miles per hour to 7.0 miles per hour over the course of the month.

For reference, on March 29, the windiest day of the year, the daily average wind speed is 7.0 miles per hour, while on December 20, the calmest day of the year, the daily average wind speed is 5.7 miles per hour.

The highest daily average wind speed during March is 7.0 miles per hour on March 31.

The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Growing Season

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season in West Valley typically lasts for 5.0 months (153 days), from around May 5 to around October 5, rarely starting before April 13 or after May 25, and rarely ending before September 18 or after October 26.

The month of March in West Valley is reliably fully outside of the growing season.

Time Spent in Various Temperature Bands and the Growing Season in March

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

The average accumulated growing degree days in West Valley are gradually increasing during March, increasing by 45°F, from 10°F to 55°F, over the course of the month.

The average growing degree days accumulated over the course of March, with 25th to 75th and 10th to 90th percentile bands.

Solar Energy

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy in West Valley is increasing during March, rising by 1.5 kWh, from 3.0 kWh to 4.5 kWh, over the course of the month.

The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

Topography

For the purposes of this report, the geographical coordinates of West Valley are 46.592 deg latitude, -120.605 deg longitude, and 1,250 ft elevation.

The topography within 2 miles of West Valley contains significant variations in elevation, with a maximum elevation change of 676 feet and an average elevation above sea level of 1,281 feet. Within 10 miles contains significant variations in elevation (2,425 feet). Within 50 miles contains large variations in elevation (11,588 feet).

The area within 2 miles of West Valley is covered by artificial surfaces (47%) and cropland (44%), within 10 miles by shrubs (42%) and cropland (42%), and within 50 miles by shrubs (55%) and trees (26%).

Data Sources

This report illustrates the typical weather in West Valley year round, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.

Temperature and Dew Point

There are 2 weather stations near enough to contribute to our estimation of the temperature and dew point in West Valley.

The estimated value at West Valley is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between West Valley and a given station.

Other Data

All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.

Disclaimer

The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.

We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.

We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.